1. Field of the Invention
The present invention relates to a photoelectric-conversion device, and particularly relates to a photoelectric-conversion device performing a phase-difference detection-type auto focusing (AF).
2. Description of the Related Art
A phase-difference detection-type focus detection apparatus realizes the AF by calculating the defocus amount of a subject (the amount of deviation from the focus point) by performing the correlation calculation for signals that are obtained through a couple of line sensors and obtaining focusing by feeding the defocus amount to the operation of an optical system. At that time, the amount of signal accumulated in a sensor should be monitored in real time, so as to change the accumulation period based on the amount of received light. The above-described configuration is exemplarily disclosed in Japanese Patent Laid-Open No. 2000-050164.
Japanese Patent Laid-Open No. 2005-328493 exemplarily discloses a configuration where a photodiode is connected to a capacitance element accumulating a photoelectric charge overflowing from the photodiode via a transistor to widen the dynamic range while maintaining a high S/N ratio.
However, performing the monitoring operation in real time while widening the dynamic range is not considered in each of the configurations that are disclosed in Japanese Patent Laid-Open No. 2000-050164 and Japanese Patent Laid-Open No. 2005-328493.